Intelligent light source with synchronization with a digital camera

ABSTRACT

An intelligent light source for use with the test of a digital camera module provides a plurality of shapes of light. A fast light pulse is created with turn-on and turn-off transitions less than or equal to one microsecond. Other waveform shapes comprise a ramp and a sinusoid, and all shapes can be made to occur once or repetitively. The magnitude of the light has a range from 0.01 LUX to 1000 LUX, and the ramp has a ramp time that has a range from microseconds to 100 ms. The light comprises of a plurality of colors created by serial connected strings of LED devices, where the LED devices in a string emit the same color. The light emanating from the light source is calibrated using a photo diode and the control of a tester by adjusting offset voltages of a DAC controlling a current through the LED strings.

This is a divisional application of U.S. patent application Ser. No.10/930,353; filed on Aug. 31, 2004, which is herein incorporated byreference in its entirety and assigned to the same assignee.

RELATED PATENT APPLICATION

This application is related to US patent application docket numberDS04-022 (now DI04-022); Ser. No. 10/930,351; filed on Aug. 31, 2004;issued Feb. 3, 2009 as U.S. Pat. No. 7,486,309; and assigned to the sameassignee as the present invention.

This application is related to US patent application docket numberDS04-023 (now DI04-023); Ser. No. 10/929,651; filed on Aug. 30, 2004;issued Mar. 17, 2009 as U.S. Pat. No. 7,505,064; and assigned to thesame assignee as the present invention.

This application is related to US patent application docket numberDS04-025 (now DI04-025); Ser. No. 10/929,652; filed on Aug. 30, 2004;issued Dec. 26, 2009 as U.S. Pat. No. 7,155,119; and assigned to thesame assignee as the present invention.

This application is related to US patent application docket numberDS04-026 (now DI04-026); Ser. No. 10/929,300; filed on Aug. 30, 2004;issued Jul. 24, 2007 as U.S. Pat. No. 7,248,347; and assigned to thesame assignee as the present invention.

This application is related to US patent application docket numberDS04-027 (now DI04-027); Ser. No. 10/929,653; filed on Aug. 30, 2004;issued Jul. 22, 2008 as U.S. Pat. No. 7,403,229; and assigned to thesame assignee as the present invention.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention is related to a light source, and in particular toan intelligent light source used to test a digital camera module that issynchronized with the digital camera module.

2. Description of Related Art

The digital camera is becoming a ubiquitous device. Not only are digitalcameras replacing the traditional film camera, digital camera devicesare being used in many other applications, such as small electronicdevices, such as PDA (personal data assistant) and cellular phones. Withthe explosion of cellular phones, the ability to take a picture and thensend that picture to another individual using a second cellular phonecomes the need to produce inexpensive digital camera modules andefficiently test these modules in large quantities. This is furthercomplicated by the many different module configurations that areemerging as a result of the many different application requirements,including fixed focus, manual focus and automatic focus as well asphysical size. Some of these modules are very small and others havesignal leads in the form of a flex filmstrip. The testing time fordigital camera module, which can have mega-pixel capability, hastraditionally been a relatively long process (approximately sixtyseconds for a module with 0.3 megapixels) to insure the integrity andpicture quality of the camera. Quality testing at a low cost has becomethe utmost of importance. This necessitates a testing capability that isfast and insures the integrity and specification of the digital cameramodule while testing a large quantity of modules.

A patent application Ser. No. 10/417,317 dated Apr. 16, 2003, is relatedto miniature cameras and their manufacturing methods that are used asbuilt-in modules in hand held consumer electronics devices such asmobile phones and PDA's. In a second patent application Ser. No.10/434,743 dated May 8, 2003, a test system is described for digitalcamera modules used as built-in modules for consumer electronics, whichperforms electrical tests, adjustment of focus and sealing of the lensbarrel with glue.

In addition there are a number of other prior art patents that aredirected to testing of digital cameras: US 20040032496A1 (Eberstein etal.) is directed to a method of camera calibration and quality testing;EP 1389878A1 (Bednarz et al.) is directed to a method of cameracalibration and testing camera quality; US 20040027456A1 (Pierce)directed to the use of calibration targets; EP 1382194A1 (Baer) isdirected to dark current subtraction; JP 2003259126 (Keisuke) isdirected to removing noise of an image; US 20030146976A1 (Liu) isdirected to a digital camera system enabling remote monitoring; JP2003219436 (Fuminori) is directed to adjustment of a pixel shift camera;US 2003142374 (Silverstein) is directed to calibrating output of animage output device; JP 2003179949 (Hidetoshi) is directed to aluminance level inspection apparatus; JP 2003157425 (Vehvilainen) isdirected to improving image quality produced in a mobile imaging phone;JP 2003101823 (Kenichi) is directed to specifying a picture data area;EP 1286553 A2 (Baer) is directed to a method and apparatus for improvingimage quality; US 20030030648 (Baer) is directed to a method andapparatus for improving image quality in digital cameras; U.S. Pat. No.6,512,587 (Marcus et al.) is directed to measurement method andapparatus of an imager assembly; US 20030002749 (Vehvilainen) isdirected to a method and apparatus for improving image quality; US20020191973 A1 (Hofer et al.) is directed to a method and apparatus forfocus error reduction; WO 2002102060 A1 (Baer) is directed to a methodand apparatus for smear in digital images using a frame transfer sensor;JP 2002290994 (Hidetoshi) is directed to a method and apparatus todetect foreign matter on the surface of a lens; JP 200223918 (Yanshinao)is directed to an image inspection device and method for a cameramodule; JP 2002077955 (Keisuke) is directed to a method and apparatusfor evaluating camera characteristics; JP 2001292461 (Keisuke) isdirected to a system and method for evaluating a camera; U.S. Pat. No.6,219,443 B1 (Lawrence) is directed to a method and apparatus forinspecting a display using a low resolution camera; U.S. Pat. No.6,201,600B1 (Sites et al.) is directed to a method and apparatus forinspection of optically transmissive objects having a lens; U.S. Pat.No. 5,649,258 (Bergstresser et al.) is directed to an apparatus andtesting of a camera; EP 0679932 B1 (Kobayashi et al.) is directed totesting an electronically controlled camera; U.S. Pat. No. 5,179,437(Kawada et al.) is directed to an apparatus for color correction ofimage signals of a color television camera; JP 03099376 (Hiroshi) isdirected to the quality of a display screen; U.S. Pat. No. 4,612,666(King) is directed to a pattern recognition apparatus; and U.S. Pat. No.4,298,944 Stoub et al.) is directed to a method and apparatus fordistortion correction for scintillation cameras.

SUMMARY OF THE INVENTION

It is an objective of the present invention to produce a light source inwhich a pulse of light has a controlled intensity and rise and falltimes that are less than a microsecond.

It is also an objective of the present invention to produce a magnitudeof the light source ranging from 0.01 LUX to 1000 LUX.

It is also an objective of the present invention to synchronize a lightpulse with a digital camera module under test.

It is still an objective of the present invention to control the lightpulse as a single pulse or a repetitive pulse.

It is further an objective of the present invention to vary the shapeand intensity of the light source comprising a ramp of light and asinusoidal shaped light.

It is further an objective of the present invention to produce a rampwith a ramp time ranging from microseconds to 100 ms.

It is still further an objective of the present invention to produce alight source with a plurality of colors each being controlled forintensity, light shape and repetition.

It is also still further an objective of the present invention toprovide calibration for each color in the light source.

In the present invention a light source is controlled by a tester forthe purpose of testing a digital camera module. The light source isconfigured from a plurality of serially connected strings of LED (lightemitting diodes) devices, each of which produces a light color. There isa plurality of LED strings producing a plurality of colors comprisingred, blue, green and infrared. Each LED string produces a differentcolor, and each of the LED strings is powered separately by a currentsource driven by a DAC (digital to analog converter). The lightemanating from the LED strings can be turned on and turned off rapidlywith a turn on transition and a turn off transition of 1 us or faster.Different pulse shapes are produced comprising a sinusoidal varyinglight and a light in which the turn-on transition is a ramp of variablelength of time. The ramp time is controlled in a plurality of time rangethan have a maximum ramp time of 100 us, 1 ms, 10 ms and 100 ms. Theamplitude of the light source is controlled in a plurality of rangeswhere, for example, the maximum comprise 10 LUX, 100 LUX and 1000 LUX,and the light from the light source can be made to be repetitive or onlyone pulse.

A tester provides controls for selecting color, intensity, shape andrepetitiveness of the light pulse. Within the tester is a frame grabberfunction, which synchronizes the light source with a clock of a digitalcamera under test (MUT). When the light source is turned on, the MUTcaptures a digital image of the light, and the frame grabber couples theimage into a memory of a computational unit within the tester foranalysis.

Data for controlling the DAC is loaded into a data memory (1K×16 bits)and is coupled to a 12-bit DAC under the control of a controller. Thecontroller comprises a FPGA (field programmable gate array), whichallows for easy upgrading of the controller operation. The data in thedata memory is used to control the light source and is coupled to theDAC, which feeds a V/I converter (voltage to current converter). The V/Iconverter pulls a current through a selected string of LED devices thatturns the resulting light on. The current is controlled such as toproduce a fast on-off light pulse or a light having a defined shape,e.g. sinusoidal, ramp or stair step. A particular light shape or pulsecan be set to be repetitive.

A photo diode is used to calibrate the light source and maintain aconsistency between the strings of LCD devices that produce thedifferent colors of light. The photo diode signal is coupled to an ADC(analog to digital converter), which couples a digital value of thephoto diode signal to the tester. The DAC that controls the currentsource (V/I converter) for a particular LED string is then adjusted tomaintain a similar light intensity between the LED strings that producethe different colors of light. This calibration capability also allowsfor adjustments resulting from aging of the LED diodes and maintainsconsistency between the different colors of light produced by the LEDstrings.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will be described with reference to the accompanyingdrawings, wherein:

FIG. 1 is a block diagram of the control of the light source of thepresent invention,

FIG. 2 is a diagram of the DAC controlling V/I converter of the presentinvention with attached calibration DAC converters,

FIG. 3 is a block diagram of the present invention showing therelationship of the frame grabber, the light source and the digitalcamera under test,

FIG. 4 is a schematic diagram of the present invention showing thecurrent source that controls the light emanating from an LED string,

FIG. 5A through 5G are waveform diagrams of light produced by an LEDstring of the present invention,

FIG. 6 is a flow diagram of the present invention for setup and controlof light from an LED string, and

FIG. 7 is a flow diagram of the present invention for the calibration oflight emanating from an LED string.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1 is shown is a block diagram of the present invention showingthe control of a light source 26. The light source 26 is contained in atest station used to test a digital camera module (MUT) 27. A tester 20provides control to a controller 21 and the tester 20 receives backdigital picture data from the MUT 27. The controller comprises a FPGA(field programmable gate array), which allows easy reconfiguration ofthe control of the light source and provides loop control to producerepetitive light waveforms. The controller 21 controls a data memory 22containing the data (16-bits×1K) necessary to control the output of theDAC 24 coupled to the V/I converter and range switch 25. Data used tocontrol the DAC is loaded into the memory 22 from an USB bus 23.

The DAC is a 12-bit digital to analog converter that controls the V/Iconverter and range switch 25 to provide a current to turn-on the lightsource 26. The V/I converter 25 has a current capacity that allows afull-scale light output of the light source for a plurality of lightintensity ranges comprising 1000 LUX, 100 LUX and 10 LUX. Each range oflight is driven with a 12-bit resolution of the DAC 24. The 12-bitresolution of the DAC allows the creation of a light intensity of 0.01LUX in the 10 LUX range. The range switch in the V/I converter 25 allowsa plurality of maximum range of currents to be produced by the V/Iconverter 25, comprising currents of approximately 50 ma, 20 ma, 2 maand 200 ua. The maximum current of 50 ma is dependent only upon the LEDdevices, which make up the light source; therefore the maximum currentis established by the LED device used. The light source is switched onand off by the V/I converter with a rise and the fall time of the lightemanating from the light source of approximately 1 us or faster.

Continuing to refer to FIG. 1, the V/I converter and range switch 25drives the light source 26, which comprises a plurality of serialconnected strings of LED devices. Each serial connected string of LEDdevices produces a different light color comprising red, blue, green andinfrared. There are spare strings of LED devices that can be used torepeat the colors used in the light source, or provide additional lightcolors. A separate DAC 24 and V/I converter 25 drives each LED devicestring. Any combination of LED device strings can be turned-on, and off,by a plurality of DAC and V/I converters simultaneously. The lightsource produces a light 30 that is received by a photo diode 28 for thepurpose of calibrating the light 30 and maintaining the calibrationthroughout the life of the LED devices. The calibration includes settingand maintaining the light intensity between the various colors producedby the LED device string for the various light ranges, 1000 LUX, 100 LUXand 10 LUX.

Continuing to refer to FIG. 1, a frame grabber function within thetester 20 synchronizes the light from the light source 26 with the clockof the MUT 27 so that the MUT can capture a digital image of the light30 that is being turned on and off rapidly by the DAC 24 and the V/Iconverter 25. The MUT 27 provides picture data 31, an Hsync signal 32, aVsync signal 33 and a clock signal 34 to the tester 20 for use by theframe grabber. The picture data 31, which is a digital image of thepicture taken by the MUT 27, is stored in a memory of the computationunit of the test system by the frame grabber. The Hsync signal is thehorizontal synchronization signal of the digital image from the MUT 27,which allows scanning out of the picture data by pixel row, and theVsync signal 33 is the vertical synchronization signal, which allows thepicture data to be scanned out by pixel column. The clock 34 is aninternal clock of the MUT 27 that is synchronized with the turning on ofthe light source to allow capture of an image of the light. The framegrabber in the test system 20 synchronizes the turning on of lightsource 26 with the clock of the MUT 27 to allow a picture of the lightof narrow time duration emanating from the light source to be capturedby the MUT.

In FIG. 2 is shown calibration digital to analog converters, CDAC1 (41)and CDAC2 (42) that are used to calibrate the DAC 24, which is used todrive the V/I converter and range switch 25 to provide current to turnon a light color from a serial connected string of LED devices withinthe light source 26. A calibration signal 40 is provided by the tester20 (FIG. 1). The calibration signal 40 is derived from a measurement bythe photo diode 28 and a controlled adjustment by the tester to providea same calibrated intensity of light for each color. Each color stringof LED devices is controlled by a separate combination of a DAC 24connected to a V/I converter and range switch 25. The calibration CDAC1adjusts the DAC 24 to calibrate the maximum value of a range of lightintensity and the CDAC2 adjusts DAC 24 to calibrate the minimum value ofa range of light intensity. There are four intensity ranges and twocalibration digital to analog converters CDAC1 (41) and CDAC2 (42) foreach color and each range of light within a color produced by the lightsource. Each color comprising a string of LED devices is coupled to aseparate combination of the DAC 24 and V/I converter 25 resulting ineight calibration digital to analog converters connected to the DAC 24for each color. An alternative to using calibration digital to analogconverters is to perform a software calibration and storing thecalibration values in memory.

In FIG. 3 is shown a block diagram of the present invention showing theinteraction of the frame grabber 50 with the light source 26 and the MUT27. When a picture is to be taken with the MUT 27, the frame grabber 50synchronizes 52 the turning on of the light source 26 with the clock ofthe digital camera MUT, which takes the picture of the light 51emanating from the light source 26. The speed at which the light 51 fromthe light source 26 is turned on and off (microseconds) requires thatthe MUT 27 and the light source 26 be synchronized in order to obtain avalid picture.

In FIG. 4 is shown a schematic diagram of the circuitry used to turn onand off a serial connected string of LED devices 60 producing a singlecolor of light. A DAC 24 is coupled to a positive input of adifferential amplifier 62 within the V/I converter 25 producing acurrent I1. The differential amplifier 62 is connected in a currentfollower mode, where the voltage applied to the differential amplifier62 by the DAC 24 is developed across a resistor R1 64 when switch S1 65is closed. The differential amplifier 62 controls the transistor device63 to conduct a current I1 until the voltage across R1 64 approximatelyequals the output voltage of the DAC 24 and creating a first range ofcurrent. Similarly when switch S2 is closed (S1, S3 and S4 open), thevoltage across R2 causes a second range of current, when S3 is closed(S1, S2 and S4 open) the voltage across R3 causes a third range ofcurrent, and when S4 is closed (S1, S2 and S3 open), the voltage acrossR4 causes a fourth range of current.

Continuing to refer to FIG. 4, the resulting current I1 is pulled from asecond current source 62 biased to a voltage Vb, which produces acurrent I2, and the current ID through the string of LED devices 60,such that I1=I2+ID. The magnitude of the current ID determines theintensity of light emanating from the LED devices 60. The serialconnected string of LED devices 60 is biased with approximately 24V andis shunted by a capacitor 61 to allow a quick discharge of currentflowing through the LED devices 60 when the light is turned off. A Zenerdiode ZD1 clamps the voltage of node N1 to approximately 12 volts toprevent saturation and provide a path for the current I2 when I1 isturned off. The purpose of the current I2 from the current source 68 isto force the string of LED devices 60 to quickly and completely turn offby starving the LED devices 60 from a source of current from parasiticimpedances and the V/I converter 25.

In FIG. 5A through 5G are shown various light waveforms produce by thepresent invention. In FIG. 5A is shown a fast light pulse produced bythe circuitry in FIG. 4 in terms of LUX versus time, where a LUX is aunit of illumination equal to one lumen (a unit of light) per squaremeter. The rise time of the light pulse is t2-t1 [1 us, and the falltime is t4-t3 [1 us. The steady state time of the light pulse is t3-t4 μ0, and is dependent upon the requirements of the test being performed.FIG. 5B shows the range of the amplitude of light measured in LUX thatis produced by the circuitry of FIG. 4. Each of the light pulses 70, 71and 72 has a rise time and a fall time of [1 us. In the lowest range, alight pulse 70 has a full-scale value is 10 LUX. Using the 12-bit DACshown in FIG. 4, a resolution of 0.01 LUX can be attained. The mediumrange light pulse 71 has a full-scale value of 100 LUX and the highestrange light pulse 72 has a full-scale value of 1000 LUX. Any lightamplitude can be chosen within each range 70, 71 and 72 between themaximum and minimum value of the range.

In FIG. 5C is shown four linear light ramps 75, 76, 77, and 78. Theramp-time of the ramp with the shortest ramp 75 ranges fromapproximately 10 us to 100 us. The ramp-time of the longest ramp 78ranges from 10 ms to 100 ms, and there are two intermediate ramps 76 and77 having a ramp time range of 100 us to 1 ms and 1 ms to 10 ms,respectively. Any ramp time that falls within the ramps 75, 76, 77, and78 can be created with the circuitry shown in FIG. 4.

In FIG. 5D is a sinusoidal shaped light waveform 80. This sinusoidalwaveform can be approximated by a light waveform of small steps 81. Asthe step size is reduced, the waveform of the light will approach theideal shape of the sinusoidal waveform 80. The average value La of thesinusoidal shaped light and the maximum value Lm can be chosen such thatthe light emanating from a string of LED devices in the light source 26never turns off or turns off during a portion of the sinusoidalwaveform.

In FIG. 5E is a light waveform, which has a raising ramp 84 and afalling ramp 85. Similar to the approximation of the sinusoid in FIG.5D, the ramps 84 and 85 can be approximate by a series of stepscontrolled by the DAC 24 and V/I converter 25 shown in FIG. 4. Thefalling ramp can be replaced by a fast turn-off transition 87 forming aramped light pulse similar to those shown in FIG. 5C. Similar theapproximation of the sinusoid using small light steps, the ideal rampshape can be approached as the steps 86 become smaller. The ramps cannotbecome any faster than the transition time of a light pulse rise andfall time shown in FIG. 5A.

In FIG. 5F is show a repetitive light waveform using the light pulses ofFIG. 5A. The length of the repetitive waveform can be any length thatcan be accommodated by the total allowable test time of the MUT. Similarto the repetitive waveform of the light pulses shown in FIG. 5 F, arepetitive light waveform of ramps of light is shown in FIG. 5G. Theserepetitive light waveforms can be of any light amplitude and time lengththat can be accommodated by the circuitry of FIG. 4. However, there isno fundamental limit to the shape and sizes of the light waveformspresented in FIGS. 5A, 5B, 5C, 5D, 5E, 5F and 5G exclusive of the lawsof physics and the requirements of the particular circuitry used toproduce the light for use in the test of the digital camera module ofthe present invention.

In FIG. 6 is shown a flow diagram of the control of a light pulse andwaveform produce by the present invention. The repetition of the lightis selected 100 by the controller 21 (FIG. 1), which selects a singleshape of light or a light waveform repeating that shape for a pluralityof cycles. The shape of the light is selected 101, which comprises apulse with fast rise and fall times, and a ramp and a sinusoid orstepped approximations thereof. The shape of the light is controlled bydata stored in the data memory 22 (FIG. 1). The intensity of light,measured in LUX, is set for each color of light to be selected 102. Theintensity can range from a maximum of approximately 1000 LUX toapproximately the finest resolution, 0.01 LUX, of the lowest intensityrange and is controlled by the amount of current coupled by the voltageto current converter 25 to a serial connected string of LED devices inthe light source 26 (FIG. 1). A light color is selected 103, whichselects one or any combination of serial connected strings of LEDdevices contained within the light source 26. Each individual string ofLED devices is separately powered from a voltage to current converter 25and each individual string of LED devices provides a light of a samecolor, comprising the colors of red, blue, green and infrared. Aselection of a combination of a plurality of LED device strings willproduce a composite light having a composite color of the selected LEDdevice strings.

Continuing to refer to FIG. 6, the light source is synchronized with theclock of the digital camera module under test (MUT) 104 using a framegrabber function within the tester. This allows the MUT to capture adigital image 105 of the light, which is turned on and off inmicroseconds, and transfer the captured digital image to a computationalunit in the tester. If a change in light color is required, then a nextlight color is selected 106, and the subsequent process steps 103through 106 are repeated. If no color change is required 107, a nextintensity setting of the light is selected 108, and the subsequentprocess steps 102 through 108 are repeated. If no additional change inlight intensity is required 109 and if a light shape change is required110, a next light shape is selected 101 and the subsequent process steps101 through 110 are repeated. If no additional shape change 111 isrequired and if the repetition of a particular light set up is requiredto be changed for the next test of the MUT, a next repetition isselected 112 and the subsequent process steps 100 through 112 arerepeated. If the no additional repetition is required of the particularlight set up 113, the process ends, It should be noted that repetitionas used here relates to the selection of a single pulse or a repetitionof a single pulse, where the single pulse is a fast pulse (FIG. 5A), aramp (FIGS. 5C and 5E), and a sinusoid (FIG. 5D), and the repetition ofa single pulse is shown in FIGS. 5D, 5F and 5G.

In FIG. 7 a process flow for the calibration of the light source of thepresent invention is shown. A light color is selected 120, which selectsa serial connected string of LED devices, where all LED devices in theselected string produce the same color of light. A light intensity ofthe selected string of LED devices is selected 121 and the light of theselected string is turned on 122 by pulling a current through the serialconnected LED devices using the voltage to current converter 25 (FIG.1). The light emanating from the LED string is measured 123 using aphoto diode and the light is calibrated 104 by adjusting the currentflowing through the LED string until the photo diode measures apredetermined calibrated value. The calibration digital to analogconverters, CDAC1 and the CDAC2 (FIG. 2), under the control of thetester 20 (FIG. 1) are used to adjust the DAC 24 (FIG. 2) until thephoto diode measures the predetermined calibration value. If thecalibration of another light intensity of the same color of light isrequired 125, the next intensity of light is selected 121 and thesubsequent process steps 122 through 125 are repeated. If no additionallight intensity settings for the light color are required and if thelast light color has not been calibrated 127, a next light color isselected 120 and subsequent process steps 121 through 127 are repeated.If the last light color has been calibrated 128, the process ends.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade without departing from the spirit and scope of the invention.

1. An intelligent light source, comprising: a) a source of light; b) ameans for calibrating said source of light; and c) a means forcontrolling said source of light to produce a timed light pulse of lightsynchronized with a light receptor.
 2. The light source of claim 1,wherein said source of light is a light emitting diode (LED).
 3. Thelight source of claim 1, wherein said source of light is a serialconnected string of a plurality of LED devices emitting a light color.4. The light source of claim 3, wherein said source of light comprises aplurality of said serial connected string, which further comprise; a) afirst serial connected string containing LED devices emitting a firstcolor; b) a second serial connected string containing LED devicesemitting a second color; c) a third serial connected string containingLED devices emitting a third color; and d) a fourth serial connectedstring containing LED devices emitting a fourth color.
 5. The lightsource of claim 4, wherein said first color is red.
 6. The light sourceof claim 4, wherein said second color is blue.
 7. The light source ofclaim 4, wherein said third color is green.
 8. The light source of claim4, wherein said fourth color is infrared.
 9. The light source of claim 4further comprising a plurality of spare serial connected stringscontaining LED devices.
 10. The light source of claim 1, wherein saidmeans for calibrating said light is a photo diode connected to a testerthrough an analog to digital converter whereby said tester controls anintensity of said light.
 11. The light source of claim 1, wherein saidmeans for controlling said source of light to produce said timed lightpulse comprises a frame grabber that controls a timing of said timedpulse synchronized with a clock of said light receptor.
 12. The lightsource of claim 11, wherein said timed light pulse is a single pulse oflight with fast rise and fall transitions.
 13. The light source of claim12, wherein said fast rise and fall transitions are less than or equalto one microsecond.
 14. The light source of claim 12, wherein said timedlight pulse further comprises: a) a first range of magnitude of saidtimed light pulse; b) a second range of magnitude of said timed lightpulse; c) a third range of magnitude of said timed light pulse; and d)said first, second and third range of magnitude are selected by avoltage to current converter function containing a range switch and themagnitude of light within said first, second and third ranges iscontrolled by a digital to analog converter connected to said voltage tocurrent converter.
 15. The light source of claim 14, wherein said firstrange of magnitude is ten LUX.
 16. The light source of claim 14, whereinsaid second range of magnitude is one hundred LUX.
 17. The light sourceof claim 14, wherein said third range of magnitude is one thousand LUX.18. The light source of claim 11, wherein said timed pulse is arepetitive sequence of said timed pulse.
 19. The light source of claim11, wherein said timed pulse is a ramp of light.
 20. The light source ofclaim 19, wherein said ramp is formed by a series of steps of lightapproximating said ramp.
 22. The light source of claim 19, furthercomprising: a) a first range of ramp times limited to one hundredmicroseconds; b) a second range of ramp times limited to onemillisecond; c) a third range of ramp times limited to ten milliseconds;and d) a fourth range of ramp times limited to one hundred milliseconds.23. The light source of claim 19, wherein said ramp is a repetitivesequence of ramps.
 24. The light source of claim 11, wherein said timedpulse is a series of steps of light approximating a sinusoid.
 25. Thelight source of claim 1, wherein said light receptor is a digital cameramodule under test.
 26. A method of calibration of a light used to test adigital camera module, comprising: a) selecting a color of light toilluminate a photo diode; b) selecting an intensity of said light; c)turning on said light; d) measuring said light with the photo diode; e)calibrating said light; f) calibrating a next light intensity andrepeating steps (b) through (f) if not all light intensities arecalibrated, else step (g); and g) selecting a next color and repeatingsteps (a) through (g) if all light colors are not calibrated, else end.27. The method of claim 26, wherein selecting said light color selects aserial connected string of LED devices producing said color.
 28. Themethod of claim 26, wherein selecting said intensity of light selects acurrent range in a voltage to current converter and an output voltage ofa digital to analog converter, which drives said voltage to analogconverter.
 29. The method of claim 28, wherein turning on said lightapplies a current from a voltage to current converter to a serialconnected string of LED devices producing said color.
 30. The method ofclaim 28, wherein calibrating said light adjusts a minimum and a maximumvoltage of an output of a DAC that drives a voltage to analog converter,thereby producing a minimum and maximum current, which in turn producesa minimum and maximum light intensity emanating from said seriallyconnected LED devices producing said light.